Method of making packing



Patented July 30, 1946 UNITED STATES PATENT OFFICE METHOD 0F MAKING PACKING John J. Fiechter, Willow Grove, Pa. Application February 9, 1943, Serial No. 475,292

This invention relates to self -lubricating fibrous packing of the type wherein a plurality of strands of fibrous material, such as cotton, rayon, or like fibres, or mixtures thereof, are impregnated with a lubricating compound andv braided together to form a continuous length of packing material.

Heretofore in making this type of packing the usual practice has been to first braid the fibrous strands together and then impregnate the braided body with the lubricating compound, usually by soaking or boiling the braided mass inthe presence of the lubricant to melt the lubricant and force it onto the braided strands.

Although the heat required to melt the lubricant caused some of the lighter or more volatile constituents of the lubricant to penetrate the braided strands, these lighter constituents had little or no lubricating value, nor any great resistance to liquids which might penetrate the surface coating of lubricant on the outside of the braided body. Moreover, the boiling or soaking action physically changed the structure of the braided body by causing it to swell, thus changing the tension of the braiding from that originally given it.

With these, and other disadvantages of the conventional pre-braided packing in mind, I have devised my present invention. According to it, I first impregnate each individual strand or filament composing the packing with the lubricating compound, and afterwards braid the impregnated strands and filaments together.

The impregnating step is carried out under conditions best calculatedto insure complete Iand uniformsaturation of the individual strands or filaments. Preferably, I rst spread open each individual strand or filament while drawing it under tension through the lubricating compound. This insures that an'adequate amount of the lubricating compound will be deposited upon all surfaces of the strand or filament. I then roll or otherwise mechanically force the lubricating compound into the opened strand or filament under sufficient pressure to insure through-andthrough impregnation thereof. The impregnated strands or filaments are afterwards wound on suitable reels and after sufcient time has elapsed for the lubricating compound to be thoroughly absorbed in the fibres thereof, the thoroughly saturated strands or filaments are passed to a, conventional braider where they are braided into a braided body of round, square, oval or rectangular cross-section.

As a result of my treatment, when the preimpregnated strands are braided into a braided 2 Claims. (Cl. 154-331) body, the lubricating compound is as thoroughly distributed throughout the interior of the body as on its exterior. This is in sharp contrast to the pre-braided packings of the prior art where the body is first braided and then impregnated with the lubricating compound and hence substantially all of the lubricating compound is applied to the outside only of the pre-braided body, and such of the lighter constituents as may have penetrated somewhat into the pre-braided body had little or no lubricating value whatever.

Other advantages of Amy pre-impregnated braidedpacking over the conventionalipre-braided packing .include the following:

When my pre-impregnated braided packing is applied in a stuffing box or the like and the gland nuts are tightened to take up on the packing, the virgin lubricant at the inside of the braided body is forced to the outside, thus re-lubricating the outside surface of the braided body with new lubricant. This is because 'the internal structure of my pre-impregnated braiding can act as a natural reservoir for the unused lubricant.

Another advantage is that when my pre-impregnated packing is used on installations which are exposed to the actionl of liquids, it offers as much resistance internally as externally to liquid penetration thereof, as well as having equally as good lubricating Values, Whereas with conventional pre-braided packing if the liquid pene-- trated the-outside coating of lubricant there is little or nothing worthwhile in the way of internal lubricant to resist further penetration,

A further advantage of my pre-impregnated packing is that by first completely and uniformly impregnating the individual vstrands and afterwards braiding them into a braided body, the structure of my packing always remains the same and whatever tension was given it during the braiding operation is not changed. With prebraided packing, the step of impregnating it by boiling or soaking the braided structure in the lubricating compound caused it to swell and the tension of its braiding to change.

Other advantages of my pre-impregnated packing are that it has a greater tensile strength than packing which has first been braided iand afterwards impregnated; and because of its capacity for re-lubricating itself when the gland nuts are tightened, it more effectively lubricates the shaft or rod to which it has been applied.

Because it is pre-treated before it is braided it will not harden or stiffen in use, nor wear itself out due to excessive swelling, because the pretreating prevents undue swelling.

In the accompanying drawing wherein I have shown a preferred embodiment of my packing and preferred method and apparatus for producing the same,

Fig. 1 is a side elevation of a length of pre-impregnated packing in accordance with my invention.

Fig. 2 is a, plan view of a machine for practicing those steps of my method which comprise rst spreading or opening up an individual strand while it is being drawn under tension through the lubricating compound, and thereafter mechanically rolling the lubricant under pressure into and through the opened-up strand.

Fig. 3 is a side elevation of Fig. 2, and

Fig. 4 is an enlarged cross-section through the packing of Fig, 1.

My pre-impregnated packing is indicated generally at I in Figs. 1 and 4. It comprises a plurality of strands II of fibrous material which are first impregnated and afterwards braided together to form a packing element.

The strands I I may be any of the usual strands customarily employed for packing purposes, as cotton, rayon, flax, asbestos or the like, or combinations thereof. The lubricant I2 may likewise be any of the usual lubricants or lubricant compounds customarily employed for packing purposes, as tallow, graphite or the like.

In producing my packing, I prefer to proceed as follows:

From a spool I3, I draw a strand II under tension over a spreading roller I4 suitably journaled adjacent one end of .a frame I5. Roller I4 is crowned, as shown, to cause the strand to be spread or opened laterally as at I El as the strand is drawn thereover (see Fig. 2).

From the spreading roller I4, the strand is drawn through a trough I'I containing the lubricant I2. Trough I'I is provided with a restricted outlet I8 which prevents surplus lubricant from adhering to the strand.

The feed of the strand is accomplished by a succession of rolls I9, which are so arranged and driven as to press or squeeze the lubricant into and through the strand as the strand passes from one roll to the next.

Rolls I9 are journaled in frame I5 and are graduated in diameter, the roll nearest the trough being smallest in diameter, and the rolls beyond said roll being of progressively increasing diameter.

All rolls are rotated continuously in the directions indicated by the arrows in Fig. 3, as by means of the intermeshing gear train 20 driven Afrom the shaft 2I of one of said rolls, as by pulley 22 and belt 23 to any suitable power source (not shown).

From the final roll of the series of squeeze or press rolls, the opened and thoroughlyimpregnated strand passes to a creel or creels 24 supported on frame I5, and thence to any suitable collection receptacle (not shown), where, after a suitable interval of time, it is braided with similarly impregnated strands in any conventional braider (not shown) and under any desired tension to form the product disclosed in Figs. 1 and 4.

From the foregoing it will be evident that as a result of rst being opened up by the spreader roller I4 to receive the lubricant I2 and then having the lubricant worked into it by means of the squeeze rolls I9, the strand is completely and uniformly impregnated with the lubricant. The impregnation is through-and-through so that when the strands are braided together as a packing element, the lubricant is uniformly distributed throughout the entire mass of packing, both inside and outside.

After it leaves the braider, the packing may be cut into strips of any suitable length and wrapped in any suitable covering for convenience of handling.

If desired, I may apply a supercial coating of graphite or the like to the braided packing before packaging it.

Although I have disclosed a preferred embodiment of my packing and a preferred method of producing it, I recognize that many minor changes may be made in both article and method. All such are to be regarded as within the spirit and scope of my invention, if within the limits of the appended claims.

What I therefore claim and desire to secure by Letters Patent is:

1. In the method of making a lubricantimpregnated braided packing which is characterized in that the several strands of ibrous material composing the packing are individually impregnated with the lubricant prior to being braided together, the steps which comprise first spreading each strand laterally and drawing it under tension through the lubricant, and thereafter and prior to braiding the strands together mechanically forcing the lubricant into and through the fibres of each opened strand.

2. In the method of making a lubricantimpregnated lbraided packing which is characterized in that the several strands of brous material composing the packing are individually impregnated with the lubricant prior to being braided together, the steps which comprise rst spreading each strand laterally, drawing each opened strand through the lubricant, and mechanically forcing the lubricant into and through the libres of each opened strand as an incident to the drawing step.

JOI-IN J. FIECHTER. 

